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Valgus Lower-Limb Deformity in the Juvenile Amputee

The clinical course of five juvenile amputees has demonstrated a myriad of presentations of genu valgum. As will be shown in the following cases, valgus deformity of the knee is not only a deformity often associated with fibular dysplasias but can be a developmental masquerader in acquired deformities. Patellar subluxation, knee-flexion contracture, and gait abnormalities were exemplary presentations of genu valgum among our amputee-clinic patients.

Case Presentations

Case 1--C.Y He was first seen at K.U. Medical Center in July 1972 at 1 month of age and found to have a right fibular hemimelia1 (Fig. 1 ). In March 1973 a Syme amputation was performed2. He was fitted with a prosthesis and began ambulating by 13 months of age. Within four months a knee-flexion contracture was noted. Detailed evaluation in January 1974 revealed a valgus knee converted to an apparent flexion contracture by external rotation of the extremity (Fig. 2 ).

In March 1975 a right proximal closing wedge varus osteotomy was performed (Fig. 3 ). By June a below-knee prosthesis was fitted with a pick-up strap but without a thigh corset. In November the sidebars were added to counteract recurrent valgus (Fig. 4 ). The valgus had persisted and progressed despite the sidebars to a point in March 1977 when he was fitted with a new prosthesis at which time he had gene valgum of 35 deg. in passive stress.

With the family relocation to North Carolina, the child's care was transferred to Duke University. When last seen in September 1981 the valgus position had become sufficiently problematic to warrant plans for a second varus tibial osteotomy in the summer of 1982.

Case 2--P.T. This patient was first seen at K.U. Medical Center in July of 1970 at the age of 5 months for a congenital dislocation of the right hip. She underwent a closed reduction and prolonged plaster immobilization which eventually produced a stable hip. At the initial visit a paraxial fibular hemimelia was noted on the left with some shortening of the left femur. In June 1974 there was a 4.8 cm shortening of the left tibia. In October 1974 there was 53 deg. of anteversion on the right and 39 deg. on the left. In December 1974 at age 4 years, she underwent a Syme amputation for a 6-cm leg-length discrepancy. After she was fitted with an expandable Syme prosthesis she did fairly well until October 1976, when she was noted to have a severe medial heel whip, indicating external rotation of the limb when moving into the swing phase. X-rays demonstrated a deficient tibial epiphysis, particularly when compared with the opposite side. Stress films showed 15 deg. of valgus, although when the patient was standing in her prosthesis there was only 5 deg. of valgus (Fig. 5 ). Anteversion on the right side, the side with the subluxed hip, in November 1975 was 59 deg. and on the left was 36 deg. In June 1977 there was 5 deg. of valgus on the nonaffected side and 17 deg. more on the opposite side. It was decided to add knee joints to the thigh lacer. This resolved the problem of the whip. Repeat anteversion series in March 1976 showed the left side to be 39 deg. and the right had decreased to 48 deg. In subsequent clinic visits she required multiple adjustments and new prostheses for her growth and development. Each PTB prosthesis has had knee hinges and a thigh lacer. When last seen in October 1981 she was doing well with her five-month-old prosthesis and had 15 deg. of genu valgum.

Case 3--D.D. This patient was first seen at 11 months of age with a constricting band of the right proximal thigh and congenital terminal deficiency through the midfoot. X-rays indicated a calcaneus and talus to be present. On May 30, 1975, a Syme amputation was performed in combination with a Z-plasty of the constricting band. A scanogram done at that time indicated 2 cm of femoral shortening and 1.1 cm of tibial shortening. A Syme prosthesis was fitted in July 1975. She did well until August 1976 when, at age 15 months, it was noted that she had a medial whip. She seemed to externally rotate the thigh when moving into swing phase. This problem persisted even after a new prosthesis was prescribed in March 1977. There was a moderate amount of "baby fat" present which made good fit difficult. It was decided to add a thigh lacer and hinges in March 1978, because of 18 deg. of valgus compared with 9 deg. contralaterally. Follow-up obtained from her consultants in Denver where her family now resides indicates that her gait is excellent without valgus interference.

Case 4--C.B. This individual was born on February 19, 1971. She was first treated at K.U. Medical Center in March 1972 for congential partial absence of the left fibula. She had removal of the congenital fibular band, a varus osteotomy of the left tibia and a percutaneous heel-cord lengthening. She was reevaluated in May 1972 and found to also have hypoplasia involving the femur (Fig. 6 ). She was again admitted to the hospital in September 1973, when a Syme amputation was planned, but this was deferred, due to the possibility that shortening of the femur may be sufficient for her to be a candidate for a Van Nes turnaround procedure. In March 1974, she was fitted with a Syme-type prosthesis with a window to allow the foot to enter. In March 1975, she was recognized to have 40 deg. of valgus at the knee. In July 1975, marked limitation of internal rotation of the left hip was noted. Gait was abnormal in that she tended to externally rotate the leg to convert the valgus into a flexion deformity. She was admitted on November 17, 1975, and underwent a Syme amputation and a tibial osteotomy to correct the valgus deformity. At that time internal rotation of the hip was 0 deg., external was 60 deg., and anteversion was 50 deg. The osteotomy healed without difficulty and she was again admitted in February 1976 and underwent a left femoral derotational osteotomy (Fig. 7 ). Internal rotation preosteotomy was 0 deg. and at the completion of the osteotomy was 45 deg., and 60 deg. of external rotation was preserved. She was subsequently fitted with an expandable Syme-type prosthesis. In October 1976 knee hinges were added, due to recurring knee valgus which measured 25 deg. and contributed to shortening which was 5.1 cm of femur and 7.2 cm of tibia. By March 1978 twin tibial varus osteotomies and a new prosthesis were used to correct the increasing valgus problem. Despite this procedure and a very functional gait, her valgus led to patella subluxation by February 1979, and in June 1980 an additional tibial osteotomy was required to decrease the valgus from 25 deg. to 16 deg. At her last outpatient visit in January 1982 she presented in 12 deg. valgus wearing a Syme prosthesis with a thigh lacer and reported good ambulation with only occasional stump discomfort.

Case 5--M.B. This child was first seen at 18 months of age when he sustained a below-knee traumatic amputation of the left leg subsequent to a lawnmower injury. Noted to have a very poor gait and knock-kneed deformity in November 1964 at 6 years of age, he had continual problems with distal bursa inflammation and abscesses. In 1966 a thigh lacer was added, in an attempt to decrease weight-bearing on the end of the stump. In July 1967 a Roux-Goldthwait procedure was performed to correct lateral subluxation of the patella. A Campbell procedure was also performed with a strip of medial capsule placed through the adductor tubercle and the patellar tendon. His prostheses were specially fabricated with a medially displaced foot and medial heel and sole wedges. These appeared to have no effect. In May 1971 he was noted to have 20 deg. of valgus in stance and with 48 deg. of valgus on stress. The patella subluxed at 40 deg. of flexion. In July 1974 it was apparent that the major abnormality was a valgus deformity in the distal femur. A medial closing wedge osteotomy was performed with a blade plate. When last seen in October 1977 he was 19 years old and had a new prosthesis. He had full knee extension, no valgus deformity, and had adapted well to the postoperative gait changes.

Discussion

The myriad presentations of genu valgum in both congenital and acquired juvenile amputees share many complexities. Not only must a clinician be aware of the changing physiologic genu valgum but he must also be suspicious of pathologic genu valgum. The reports of Salenius and Vankka1 and others2, relating the tibiofemoral angle to the age of the child, documented the long-observed progression of newborn genu varum which straightens between the first and second year and continues into valgus in the third year, only to resolve spontaneously in the following years. Should the tibiofemoral angle fall within the appropriate range for the age of the amputee, as in most cases in our series, the treatment becomes a watchful process. With congenital abnormalities of epiphyseal supporting soft tissue structures, the predictability of physiologic improvement of the valgus falls into question. If consideration is given to the theory that toddlers learn to balance and ambulate with a wide-based gait which can relatively overload the medial tibial epiphysis and thus delay its growth, then a prolongation of the awkward initial period of ambulation, such as with a limb deformity and/or amputation, may delay physiological correction by virtue of excessive medial stress7. The valgus positioning producing medial tibial epiphyseal arrest may be a factor in the persistence of the valgity.

We know that many congenital lower-limb abnormalities are associated with epiphyseal dysplasias, particularly fibular hemimelia. These are usually unilateral and may be asymmetric as in the cases of C.Y. and P.T. The resultant deficient tibial plateau led to the pathologic valgus in these patients and required operative intervention for correction in one while conservative management has proven sufficient for the other. When external rotation accompanies the genu valgum a pseudo knee-flexion contracture appears. Without the foot and other normal contours of anatomy for orientation, these torsional abnormalities serve only to confuse the issue, as was the case with M.B., who presented with recurrent patellar subluxation. The severity of the malalignment came to surgical interference at 3 years of age-the height of his physiologic valgus. Of interest is the fact that his amputation was acquired and not associated with epiphyseal dysplasia. P.T., C.Y. and C.B. also had external rotational involvement of the extremity which converted the limb to a knee-flexion contracture appearance with a medial heel whip. Restriction of internal rotation of the hip was noted in two cases, one requiring a derotational osteotomy. Relative retroversion of the hip could cause this. In case 2 the anteversion was less on the affected side, since it was not decreased with respect to normal. In case 4 the anteversion was increased. Thus, the range of hip rotation is more important and not dependent on the degree of anteversion. Other factors, such as acetabular anteversion and capsular length, also control hip-rotation range and position. External knee hinges with thigh lacers were successful in two of the five patients in controlling valgus progression and obviating the need for surgery. One deformity had been the result of a defective lateral tibial epiphyseal development in association with ipsilateral congenital dislocation of the hip and fibular hemimelia. The second was a relatively mild valgus in association with partial forefoot deficiency without concommitant epiphyseal disturbance.

Conclusion

In our patients the age of presentation often coincided with failure of expected physiologic valgus-deformity correction. The reason for the delayed reversal demands careful observation in the prosthetic-wearing population as often forces are at work which may produce progressive valgus or induce secondary epiphyseal and supporting structure (e.g., ligamentous) changes about the lower extremities. Careful individualized attention with frequent clinical and roentgeonographic evaluation can best provide and maintain these youthful amputees with functional ambulation. Should conservative management fail, again an individualized approach contemplating the age, associated structural abnormalities, and growth potential within each epiphyseal segment of the patient, and potential of future procedures, i.e., Van Nes turnaround, will yield the optimal decision.

Conclusions:

Valgus deformity of the knee may develop with both acquired and congenital amputations in children.

The deformity may be due to a deficiency in either the femur or the tibia and be located in the epiphysis, metaphysis, or shaft.

Patellar subluxation, medial heel whip, or apparent knee flexion contracture may be due to genu valgum.

Valgus deformities tend to present when the genu valgum of the toddler fails to decrease normally.

All cases of excessive valgus were successfully treated by surgical correction of the deformity, although repeat correction and orthotic control may be required.